<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .pink {
            background-color: pink;
        }
    </style>
</head>
<body>
    <button class="pink">按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>   
    <script>
        let btns = document.querySelectorAll("button");
        for (let i = 0; i < btns.length; i++) {
            btns[i].addEventListener('click', function() {
                document.querySelector('.pink').className='';
                this.className='pink'
            });
        }
    </script> 
</body>
</html>
